The present invention relates to ink-application arrangements for printing machines in general, and more particularly to a device for adjusting the position of an ink knife relative to an ink pickup roller to adjust a passage for an ink contained in an ink reservoir.
Adjusting devices for adjusting the thickness of ink zones along the length of the ink pickup roller are known in the art. Those devices normally include a number of adjusting elements arranged lengthwise of the ink pickup roller and operated to move the stripped edge of the ink knife to and from the ink pickup roller to thereby adjust the ink zones formed between that stripped edge and the circumferential surface of the ink pickup roller.
For example, the patent DD-PS No. 139 114 discloses a device for adjusting an ink knife relative to the ink pickup roller including angle levers pivotally supported in the housing of the ink applicator. One arm of such a lever bears against the ink knife whereas the second arm of the lever is actuated by a respective set screw of a screw-type setting arrangement.
The disadvantage of this otherwise satisfactory device is that due to set-back forces exerted on the ink knife the mutual influences on the neighboring ink zones caused by the action of adjacent set screws can not be avoided.
Furthermore, with conventional motion-transmitting elements translating the motion of the setting screw into the motion of the ink knife, an accurate reproducible adjusting of the ink zones is impossible because reversing plays occur within transmitting elements during the changing of the positions of those elements.
The patent DE-AS No. 1 243 696 shows a device in which the set screws actuate the ink knife in the proximity of its lower edge through a lever. In this design, transverse pins coupled to the lower side of the ink knife by a form-locking connection engage the lever with their opposite ends. Although this device in part avoids the mutual influence of adjacent ink zones on each other because the ink knife is adjusted at both sides thereof, reversing plays occuring in the motion-transmitting elements, when their positions are changed, can not be eliminated.